IN “Let Me Try Again,” a song Paul Anka wrote for Frank Sinatra, the line “I was a fool to doubt you” looms large. At the former Westbury Music Fair (re-christened the North Fork), Anka sang the song but didn’t listen to his words.

The singer, who just turned 64, took a chance this year and made a record where he interpreted 14 great rock songs. It’s a risky disc for a guy who had his first big hit in 1957 – 48 years ago.

At Westbury, the dapper crooner packed the house as he does annually and rendered a dizzying array of hits that left the uninitiated in awe, wondering how one man could have penned so many of the great songs of the last 40 years.

Unfortunately, the new album, “Rock Swings,” hardly got consideration in that set.

It was a vote of no confidence for this new material that was doubly amplified by the fact that his Irving Plaza gig earlier this week – a show that could have showcased his considerable talents to a new generation – was nixed.

By foolishly doubting himself, Anka nestled deeper into his niche as a museum piece instead of a vibrant musician.

In the middle of his one-night stand, which featured his compositions including “You Are My Destiny,” “Lonely Boy,” “She’s a Lady” and “My Way,” Anka squeezed in covers of Bon Jovi’s “It’s My Life” and Eric Clapton’s “Tears in Heaven.”

Both were nicely delivered with his signature overwrought, emotional vocal style that critics love to hate but fans adore. But where were the powerhouse songs from “Rock Swings” like Van Halen’s “Jump,” Soundgarden’s “Black Hole Sun,” Nirvana’s “Smells Like Teen Spirit,” Oasis’ “Wonderwall” and his incredible take on R.E.M.’s “Everybody Hurts”?

Paul, you still have the chops, and you’re a terrific old-school showman. Stop doubting the new disc, quit using the oldies act as a crutch and get your butt into hip urban joints in Manhattan, Los Angeles and Chicago. Nobody’s saying to ignore “Diana,” “Put Your Head On My Shoulder” or “My Way” – that’s who you are – but you have to trust yourself, say what the hell and stop playing it safe.

Take a chance and do a mash-up with Jay-Z to get your juices flowing again.